I'm with safoster71 on this.
I use the magnetic lasso tool in Photoshop all the time. Without something similar I just cannot leave Photoshop. I often do complex selections of things like a cyclist at the head of a pack of others, so you have a huge amount of detail all crammed together, a mix of wheels, jerseys, handlebars, cables, levers, spokes, gears and chains etc. I need to be able to select out one at the front to use independently.
I have tried the options suggested above and they are just way too slow and clumsy compared to the magnetic lasso tool, and hand drawing selections means I end up with all the imperfections of my wobbles and also pointed angles instead of smooth curves. I have to have the image well zoomed in to see the detail and then I reach the bottom of the visible area and I cannot keep going down until I stop, and then scroll down, and have to then reselect and add to the already selected area. Just not practical.
Hope you can add something like the magnetic lasso tool or even like the Pixelmator lasso tool, which would be better than the options now, but to be honest I still wouldn't switch from Photoshop without a good alternative to the magnetic lasso tool. Perhaps too complex to add soon?
I love the potential of this app, I have looked at Pixelmator several times but it just didn't attract me. Photo I fell in love with straight away, and would love to switch from Photoshop. Keep up the good work!!!